Written by Topher Kessler
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- Welcome to our Mac Wi-Fi troubleshooting guide, which offers fixes for situations where Wi-Fi isn't working, your Mac refuses to connect to the internet, you MacBook won’t connect to WiFi but.
- KeepAlive is a freeware application that keeps your (wireless) connection alive. It does this by sitting in your task bar and regularly pinging a certain host.
- Additional features include keep alive, auto ascii/binary transfer and more. A nice program for beginners and advanced user alike. Download FileZilla for Mac is a powerful file management software for FTP access to your Web site's server!
Yesterday we found that some laptop owners who applied the 10.5.8 system update were having difficulties connecting to their WiFi networks. There are a variety of reports regarding this issue, some of which claim the WiFi cannot connect at all, others that claim WiFi is slower, and some discussing only intermittent WiFi connectivity. Despite these, many other people who have updated (including us at MacFixIt) have not had these WiFi problems even on the same hardware reported.
It appears this problem for the most part happens when people run on the battery, as described in several Apple discussion threads (1, 2). For instance, when plugged into A/C power, servers can be pinged with a consistent response time; however, when switching over to battery the response time will become very erratic. While this indicates the possibility of specific hardware incompatibility, this problem has been shared by both MacBook and MacBook Pro owners. Additionally, owners of the same type of computer with the same Airport card firmware and hardware revisions have had different effects by the update, with some losing connectivity and others running just fine. People with differing router setups also have experienced the same problem, indicating the network is not to blame.
All evidence points to a software problem, or at least how the software is interacting with specific hardware settings, and as such there are several potential fixes that can be attempted:
- Reset the PRAM and SMC Since this appears to be a power issue, some setting in the PRAM or SMC may be contributing to the problem, so first try resetting these controllers. To reset the PRAM, reboot and hold the options-command-P-R keys all at once; the system will continually reset and make the boot chimes as long as these keys are held. Let the system reset a couple of times and then release the keys and allow it to boot normally. To reset the SMC for portable systems, refer to this Apple knowledgebase article: http://support.apple.com/kb/HT1411
- Clear system caches There may be a boot cache or kernel cache error that is contributing to this problem. Perhaps a setting or driver in the caches is being loaded incorrectly if the system has not cleared the boot caches properly after updating, so you can do several things to ensure the system's caches are flushed and reset. The first is to boot into Safe Mode, which will run some maintenance scripts at startup and clear some caches. When in Safe Mode, run a third-party cache cleaning utility and clear all system caches, especially the boot and kernel caches. Several that we recommend are the following:
- Remove and re-add Airport networking service Go to the Network system preferences and remove the Airport service, clicking 'Apply' to ensure the new configuration is saved. Then click the ' ' button and add the service back, saving it with 'Apply' as well.
- Reapply the combo updater Download the OS X 10.5.8 Combo updater and then boot into Safe Mode (hold shift at startup) and apply the updater. Users have found that running the updater twice has cleared some other problems, such as the permissions errors, and has helped a few with their WiFi connectivity issues.
Overall, while this problem may require Apple to address it, these suggestions should get some people up and running since the problem does not appear to be an incompatibility with specific hardware. In the mean time, if you are not able to clear the problem, you should still be able to connect to WiFi networks by keeping A/C power plugged in.
UPDATE: It appears Apple is aware of this problem and is looking into a fix. We will report any updates as they come.
Questions? Comments? Send us feedback: http://www.macfixit.com/contact
Be sure to check us out on Twitter and the CNET Mac forums.
Be sure to check us out on Twitter and the CNET Mac forums.
Topher has been an avid Mac user for the past 10-15 years, and has been a contributing author to MacFixIt for just over a year now. One of his diehard passions has been troubleshooting Mac problems and making the best use of Macs and Apple hardware both for family and friends, as well as in the workplace. He and the newly formed MacFixIt team are hoping to bring enhanced and more personable content to our readers, and keep the MacFixIt community going here at CNET. If you have questions or comments for Topher or the other MacFixIt editors, feel free to contact us at http://www.macfixit.com/contact
ResourcesMac OS X plist files for use with launchd demonstrating how to use KeepAlive
- at.obdev.LittleSnitchUIAgent.plist is a basic 'KeepAlive' plist.
Note the
And
Together, those tell
launchd
to run the program listed in ProgramArguments
as soon as the user logs in, and keep it running as long as they are logged in, no matter what:Now if
Little Snitch Agent
is terminated for any reason (i.e. crash or kill
) it will automatically restart.At first you might be tempted to create several plists like this to keep all of your favorite apps running all of the time.
Don't do that.
Think about what happens if an app you have designated as
KeepAlive
needs to be updated. What happens? The app tells you it has an update, you download it, the app quits and then -- uh, it restarted. Did it have a chance to finish updating? Are you sure?Occasionally,
KeepAlive
apps can interfere with rebooting or logging out.In most cases, a better solution is to use
KeepAlive
together with SuccessfulExit
.KeepAlive and SuccessfulExit
For example com.tjluoma.keeprunning.moveaddict.plist shows how to create a plist to keep an app running all of the time unless it exits cleanly (i.e. the user told it to quit). It uses
KeepAlive
but adds a check called SuccessfulExit.
If an app exits 'successfully' (technically, with an exit code = 0) then the app will not be automatically restarted (kept alive). However, if the app crashes (exit code not equal to 0) then it will be automatically restarted. Here is the relevant bit of launchd
code:This is handy if you have an app which occasionally crashes, especially if that app is one which runs in the background or the menu bar where you might not notice immediately.
KeepAlive
and NetworkState
Another option is
KeepAlive
and NetworkState
as shown in com.tjluoma.keeprunning.mail.plistwhich tells Mail.app to always keep running as long as we have a network connection.Here is the portion of the plist which specifically deals with the 'is the network up?' part:
Important note #1:
launchd
considers the 'network' to be 'up' if you have an IP address. However, it is possible that your local network could be up but your connection to the Internet is down. For example, right now my ISP is offline, but I am connected to my local Wi-Fi network, so as far as launchd
is concerned, the 'network' is up. Just remember that 'Network is up' does not necessarily mean 'Internet is up/accessible.'Important note #2: It is also important to remember that
launchd
will not quit an app just because the network connection goes down. The only time the KeepAlive
would be used is if the app quits, at which point launchd
will check and say 'Is the network up?' and if the answer is yes, it will relaunch the app. If the answer is no, it will not relaunch the app.Installation
Unless otherwise noted, plists should be placed in the '$HOME/Library/LaunchAgents' (where '$HOME' represents the path to your home directory, for example: /Users/sjobs/Library/LaunchAgents/
How to start a new launchd plist
By default,
launchd
will load the '.plist' files from '$HOME/Library/LaunchAgents' when you log in. If you want to start a new .plist, you will have to tell launchd
to load it. To do this, launch Terminal.app and type:And then:
(change 'com.tjluoma.keeprunning.mail.plist' to the filename of whichever plist you want to load)
How to tell launchd
that you have changed an existing plist
If you have changed an existing plist and want the changes to be recognized right away, you have to unload it, and then reload it:
How to uninstall / remove a plist
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Again, in Terminal.app, do:
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And then either move it to the trash:
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Or delete it: